1. Field of the Invention
The present invention relates to a vehicle lighting device including a light emitting element, such as a light emitting diode, as a light source.
2. Description of Related Art
In recent years, lighting devices, which use as light sources light emitting elements, such as light emitting diodes, have been developed for use in vehicle lighting devices such as headlamps.
In relation to the development of these lighting devices, Japanese Patent Publication No. 2001-283616 describes a vehicle lighting device including a primary reflector which reflects light from a light emitting element disposed on an optical axis extending in a longitudinal direction of the lighting device in such a manner as to be directed towards the front of the lighting device towards the rear of the lighting device and a secondary reflector which reflects the light from the light emitting element that is reflected on the primary reflector towards the front of the lighting device. In the vehicle lighting device described in JP-A-2001-283616, the shape of a reflecting surface of the primary reflector is the shape of an ellipsoid of revolution, which takes a light emitting center of the light emitting element as a primary focal point and a point positioned forwards of the primary focal point on the optical axis as a secondary focal point.
While the utilization factor of bundles of rays of light from the light emitting element can be enhanced by adopting the vehicle lighting device described in the aforesaid JP-A-2001-283616, in the vehicle lighting device so described, there is a problem that light emitted from this vehicle lighting device cannot be accurately controlled since not only the light from the light emitting element that is reflected on the primary reflector, but also direct light from the light emitting element, are designed to be incident on the secondary reflector.
The invention was made in view of this situation, and an object thereof is to provide a vehicle lighting device including a light emitting element as a light source which can enhance the utilization factor of a bundle of rays of light from the light emitting element and also accurately control light emitted therefrom.